I was thinking of airborne electromagnetic (AEM) surveys (e.g., https://www.ramboll.com/projects/water/aem-mapping-californi...) when I wrote that, but after checking my notes, I found that I had misremembered: I actually hadn't been able to find any ADS-B tracks that were clearly survey flights!
That tracks .. geophys surveys, whether active (sending out signal to ground and listening to the return) or passive (bat airs across the spectrums), are predicated on having as 'neutral' a recording post as possible .. blatting out radio spectrum data that would have to be removed from the record in post just isn't "the way".
Aeromag and radiometrics tend to be low level and tight; 80m ground clearance, 200m line spacing (unless for regional levelling of multiple small infill surveys).
Photogrammatic sureys are higher with much wider spacing, the frames are large and there's really only need for a 50m or less overlap to get a good broad area mosaic.
I'm guessing you have routines to analyse and classify flight activity by path characteristics and coarsely bucket activity?
